Corneal dystrophies are usually:

Ans is 'b' i.e. Primarily bilateral "A corneal dystrophy is classically bilateral, progressive, and isolated to the cornea. The disorder is inherited, characteristically in a dominant fashion, and often appears clinically to involve only one layer of the cornea. YanoffCorneal dystrophyCorneal dystrophies are inherited disorders in which the cells have some inborn defects due to which pathological changes may occur with passage of time leading to development of corneal haze in otherwise normal eyes that are free from inflammation or vascularization.There is no associated systemic disease.Dystrophies occur characteristically bilateral.Dystrophies manifest occasionally at birth, but more usually during first or second decade and sometimes even later in life.Usually autosomal dominant.